A130593 Evil semiprimes.

6, 9, 10, 15, 33, 34, 39, 46, 51, 57, 58, 65, 77, 85, 86, 95, 106, 111, 119, 123, 129, 141, 142, 159, 166, 169, 177, 178, 183, 187, 201, 202, 209, 215, 219, 221, 226, 235, 237, 249, 267

Offset

1,1

Comments

Products of two (not necessarily distinct) primes such that the product has an even number of 1's in its binary expansion. Non-evil semiprimes are odious (A000069).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

E. Fouvry, C. Mauduit, Sommes des chiffres et nombres presque premiers, (French) [Sums of digits and almost primes] Math. Ann. 305 (1996), no. 3, 571--599. MR1397437 (97k:11029).

Formula

A001358 INTERSECTION A001969.

Mathematica

Select[Range[300], PrimeOmega[#]==2&&EvenQ[DigitCount[#, 2, 1]]&] (* Harvey P. Dale, Nov 08 2011 *)

Prog

(PARI) list(lim)=my(v=List(), t); forprime(p=2, lim\2, forprime(q=2, min(p, lim\p), if(hammingweight(n=p*q)%2, , listput(v, n)))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Mar 26 2013

Crossrefs

Cf. A000069, A001358, A001969.

Sequence in context: A020219 A175634 A134622 * A328234 A051221 A029843

Adjacent sequences: A130590 A130591 A130592 * A130594 A130595 A130596

Keyword

easy,base,nonn

Author

Jonathan Vos Post, Jun 16 2007

Extensions

Corrected (a(21)=129 added) by Harvey P. Dale, Nov 08 2011

Status

approved